1. Field of the Invention
The present invention relates to measurement devices and methods, and more particularly, to devices and methods for foot contour measurement.
2. Description of the Related Art
Foot contour measurement methods typically consist of sampling the surface of the foot using either mechanical (such as plaster et al.), electronic, electromechanical or electro-optical means.
A preferred device is manufactured by the assignee of this application. The same also holds a number of patents covering various methods to measure feet and to fabricate a custom machined insoles for the foot. One such device, a “Contact Digitizer”, uses regularly spaced gauge pins that are urged upwards under the subject foot, as disclosed in U.S. Pat. Nos. 4,449,264, 4,454,618, 4,517,696, 4,876,758, and 5,941,835. These gauge pins are measured for position relative to a datum surface that is then processed to produce a digital model of the undersurface of the foot. This device is preferred over other technologies due to the ability of the gauge pins to deflect the soft tissue encountered when upwardly urged against the undersurface of the foot. The machine therefore makes allowances for the areas of the foot with soft tissue or where there may be underlying bone structure. This produces a data set which incorporates these allowances. When this data is used to produce a support for the foot, a more effective device is produced.
It is also possible to design electromechanical contour sampling devices with variations like an array of trailing swing arms that translate in one axis while measuring the position of the swing arms to determine the shape of the subject surface.
Such devices have been successfully applied worldwide for the measurement of the foot for the fabrication of custom foot support appliances (foot orthotics).
Prior art devices used gauge pins which were urged upwards against the undersurface of the foot by a pneumatically actuated diaphragm. The foot is placed against the top of the device and a device is slide under the toes to restrict the upwards force of the gauge pins under said toes.
The gauge pins are urged up by a diaphragm until they contact the undersurface of the foot. A separate mechanism is used to “lock” or freeze the gauge pins at the height attained. At this time the subject foot could be removed from the device. The gauge pins would retain the shape of the undersurface of the foot. A measurement means or measurement mechanism was used to determine the relative heights of the gauge pins. The resulting values were saved in a processor for storage and possibly subsequent manipulation and ultimately used to direct the operation of a robotic milling machine to produce the finished custom insole.
The prior art devices therefore required the following steps involved in the measurement of a foot: 1) place the foot on the device, 2) center the foot on the device using an incorporated heel guide, 3) slide the toe plate into position to restrict upwards motion of the gauge pins against the toes, 4) activate the diaphragm to urge up the gauge pins, 5) activate the locking mechanism once the gauge pins have contacted the subject foot, 6) remove the subject foot, 7) activate the measurement mechanism to determine the relative heights of the gauge pins, and deactivate the locking mechanism and the diaphragm to reset the gauge pins for the next measurement. Each of the steps must be repeated for each foot.
The prior art measurement mechanisms consisted of two measurements of the gauge pins in opposite directions. The processor uses these two measurements to determine an average value. It has been determined that the differences in these two measurements is so small as to be of little accuracy value. And by only measuring the gauge pins in one direction, at least 50% of the time used in measuring the gauge pins can be saved. It has also been determined that the measuring time can be further reduced by simply speeding up the scanning process. This reduction in scanning time eliminates the need for a locking mechanism.
The locking mechanism was a requirement in the prior art design due to a number of factors. The measurement mechanism was fairly slow and there was a risk of foot movement during the measuring process. Also, because it was desired to make a very accurate device, it was determined that for complete accuracy of gauge pin position, the pin must be locked in place at some point in time and then measured.
If the measurement could be done faster, then there is less risk of foot movement during the scan. By changing some of the measurement techniques, the scan time can be reduced by approximately 70%.
It is desirable to apply this technology to a broader market than simply in the medical applications where it is used presently. Prior art devices, however, do not lend themselves well to the broader (retail) market. The device is moderately fragile (each gauge pin can be sheared off) and the top surface is subject to damage by accidental spillage of liquids seeping into the interior of the device.
There is a need to provide contour sampling technology to a broader market than simply in the medical applications where it is used presently.
There is also a need to reduce the number of operator actions required to measure a foot to improve the simplicity of a contour sampling device.
There is a further need to enhance the prior art devices with new and unique improvements to address these shortcomings.
There is yet a further need to eliminate the need for a locking mechanism or the need for a toe plate.
There is also a need to eliminate the concern for device contamination and resulting failure due to contaminants being introduced through the top surface of the device.